IMPORTANT NOTE:
IF YOUR LOG HAS LINES LIKE THIS IN IT
Downloaded 'minecraft.jar' matches MD5 of version '1.4.2'.
[10:14:21] [sEVERE] Starting download of 'null', with 3 trie(s) remaining
[10:14:21] [sEVERE] java.net.MalformedURLException
THIS FIX WILL DO NOTHING FOR YOU AS IT IS A SEPARATE ISSUE
Launcher Version: 1.0.2.0
Operating System: Win7
Java Version: jdk1.7.0_07 (64 & 32bit)
Antivirus Program: None.
Description of Problem:
While updating through the Technic Launcher, it will attempt to download minecraft.jar 3 times and fail with the message Update Failed!. After checking my log files I can see that the problem is that the minecraft.jar files it attempts to download do not match the md5 hashes of what the launcher has.
A solution: download Minecraft 1.2.5 from Mojang directly (url: http://assets.minecraft.net/1_2_5/minecraft.jar ), rename the file you just downloaded to minecraft_1.2.5 and place that file into your .techniclauncher/cache folder. - NOTE: If you're on windows and have enabled file extensions to be shown (the default is that they are not shown) then you will need to rename the file to minecraft_1.2.5.jar - do not do this if you are unsure. - NOTE: If you're using Internet Explorer, it will download the file as a zip file which will require you extract it (usually right click > Extract), you could alternatively download the file using another web browser such as Firefox, Google Chrome, or Opera.
You can find your .techniclauncher/cache in %appdata%/.techniclauncher/cache on windows, and in ~/.techniclauncher/cache on most linux distros. I believe the same folder would be under /Users/USERNAME/Library/Application Support/.techniclauncher/cache on OSX but I cannot confirm. - NOTE: For OSX the folder may simply be called techniclauncher without the leading period.
Error Messages:
Update Failed!
Error Log:
[19:51:05] [sEVERE] Starting download of minecraft, with 3 trie(s) remaining
[19:51:13] [sEVERE] Downloaded 'minecraft.jar' does not matche MD5 of any known minecraft version!
[19:51:13] [sEVERE] Starting download of minecraft, with 2 trie(s) remaining
[19:51:20] [sEVERE] Downloaded 'minecraft.jar' does not matche MD5 of any known minecraft version!
[19:51:20] [sEVERE] Starting download of minecraft, with 1 trie(s) remaining
[19:51:29] [sEVERE] Downloaded 'minecraft.jar' does not matche MD5 of any known minecraft version!
[19:51:29] [sEVERE] java.io.IOException: Failed to download minecraft